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HELP!! Need input on problem
Guys,
I've got 600 near-perfect miles on my Everett- Morrison and started having problems yesterday. I'm running a 460 Super Cobrajet with a MSD 6AL, Performance distributor and Inferno coil. Carb is a 750 Mighty Demon. The engine quit running three times during slow speed and once at 60 mph. It's as if the ignition stops providing spark and the engine dies. All gauges and fans continue to operate normally. Once stopped, the engine cranks right back up seconds after cutting off as if nothing happened. There is no consistent trend when the failure occurs and no warning signs. I've tried to duplicate the problem while the engine is idling by checking the harnesses to no avail. Pulled plugs and they're perfect and the engine is performing normally. I'm leaning toward a bad coil but would like to hear your input. Thanks Greg |
I doubt it's a coil.. those usually fail completely or you would notice diminished spark.
I would start by looking into wiring connectors and grounds or vapor lock on the fuel. |
xlr8or
Thanks for the reply. Tell me more about vapor lock. Greg |
Sounds like a ground wire problem, that said are you sure its not a fuel problem? when it stalls, is there still fuel in the carb? is it a mechanical pump or electric? the best way to tell if it is fuel is to turn off the ignition immediately after the problem occurs and check the carb for fuel, if you open the throttle with the air cleaner off it should squirt fuel into the manifold and you can then eliminate fuel as a suspect. If there is no fuel then you need to back track the fuel delivery system. Finding an electrical gremlin is a little more difficult, the best way is if the problem was not intermittent, as you described it, I would look for loose wires in the ignition system, its usually a ground problem.
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Cobra Bill,
I'll check the carb next time it happens. I ruled that out due to the engine starting immediatly after the failure, but pulling the filter will confirm. Good advice. Thanks Greg |
Greg
I had the exact same problem that started out happening once or twice a year. Then it started happening a little more often and sometimes it would take a couple of minutes before it would re-start. At least that gave me some time to rule out fuel, loose wires etc. The definitive test was that I ran a hot wire directly to the coil through a temporary switch so that the next time it happened, I could flip the switch and rule out everything but the coil. Guess what, it was a bad coil. Hope your solution is simple to find. Jim |
MSD boxes have been known to fail if they have a poor ground, so you may want to insure your ground to the box is good.
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Thanks jwd.
Its cheap and will be easy to rule it out with a swap. Greg |
Woodz428
I'll check the ground - thanks for the input Greg |
Could be the coil. I've had two coils fail intermittenty. Once they heat up and expand they either go to an open circuit or short out. Once they cool you can fire it back up again---only to have it die.
Get your DMM out and go for a drive. When it dies, coast to the side of the road and check the voltage at the coil posts. I'm willing to bet you'll find the + and - sides at the same voltage. DD |
to eliminate the easy problems first when it dies you may want to run back to the fuel cap. If you open and hear a whoosh...maybe an issue with fuel tank/cap venting. Just heard about this happening to someone today.
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DD and ekrupa2
Thanks and I'll check the cap. Greg |
maybe
If you have an oil filled coil (ACCEL) that is mounted on it's side, they will fail. When mounted on it's side an air bubble in the coil exposes the coil wires and they burn into. Check your distributor cap button, the small brass/metal button at the top of the cap. It may be burned up. The 8 contacts may be burned. These are some of the problems I have seen with oil filled coils mounted on their side.
Fuel filters, to small or more than one, restrict fuel flow. Electrican fuel pumps mounted to high or to far from the gas tank. Electric pumps are pushers and can not "pull" the fuel from the tank if they are mount to far from the tank. Floats set to low in your carb. Dwight |
Don't discount the possibility of a bad ignition switch.
Next time you have it running, wiggle the key a little. It could be 1/100 of a turn away from shutting off, due to poor or mis-located contacts inside the switch. Mine was doing that. I happened to notice that all of the gauges went dead at the same moment the engine died. Fortunately mine did it before I ever got it on the road. |
Hey Greg,
Already some great advice on items to check. My own experience on coils is they can be intermitent then bad. An old school way to check without scope or other test equipment is color of spark. A quick visual test is to watch the spark at the end of the wire. The color should be a neon blue. A yellow or orange color leads me to question the coil. Battery or supply voltage needs to be close to 14VDC with engine running and no less than 12.5 VDC. Just one of many possible problems but this one is easy to check. Good luck and hope you fing it quick and easy. Jeff C |
I think Woodz428 is close to right. The MSD box is probably failing. Depending on your ignition distributor, it may be possible to bypass the
MSD and run off the distributor. Your MSD instruction book may cover the fault trace, or give MSDs tech line a call. |
MSD overheating?
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I don't trust msd ignition boxes, why do you think NASCAR cars have 2 of them with a switch. I have burned out 2 of them and I gave up on them.
try a new one, you should have a spare anyway. |
You guys are great! I can't thank you all enough for the input. I'll go through each of your recommendations and eventually track the problem down.
Greg |
Magnetic pickup?
... was having this exact discussion at this month's luncheon. Don't know about your distributor, but MSD distributors chronically fail with a bad magnetic sensor module. Same symptoms you report.
Good luck, Sam |
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